Grinding machine in which the force applied to a guide template is advantageously reduced

ABSTRACT

A grinding machine for abrading a trochoidal form surface of a work-piece which includes a male template secured to the under surface of a work piece operating table which is adapted to move to create a trochoidal form, and follower means for transmitting motion corresponding to a cam face of the template to a follower table through rotary arms. In rough grinding, the follower means can be disengaged from the template for high speed abrasion, while in finishing grinding following the cam face of the template, the force applied to the template is advantageously reduced for prolonged life of the template and high working efficiency.

United States Patent Hayashi et a1.

[ 1 GRINDING MACHINE IN WHICH THE FORCE APPLIED TO A GUIDE TEMPLATE IS ADVANTAGEOUSLY REDUCED [751 Inventors: Kunihisa Hayashi; Yoshihiro Tadera, both of Kure, Japan [73] Assignee: Toyo Kogyo Co., Ltd., Hiroshima,

Japan [22] Filed: Oct. 17, 1974 [21] Appl. No: 515,715

[30] Foreign Application Priority Data Oct, 23 1973 Japan 11415-119601 [52] US. Cl 51/101 R; 5l/l65.89; Sl/DIG. 32 [51] Int. Cl B24b 5/06 [58] Field of Search 51/50 PC, 101, 165.89, Sl/DIG. 32; 90/134; 82/].3; 74/567, 569

[56] References Cited UNITED STATES PATENTS 3,750,345 8/1973 Kolcsar .4 5l/D1G. 32

[ Sept. 9, 1975 3,800,621 4/1974 Hoglund Sl/DIG. 32 3,813,818 6/1974 Hayashi 51/D1G. 32 3.828.481 8/1974 Uhtenwoldt 5l/D1G. 32

Primary Examiner-Al Lawrence Smith Assistant Examiner-Nicholas P. Godici Attorney, Agent, or FirmLind & Ponack Wenderoth [57 ABSTRACT A grinding machine for abrading a trochoidal form surface of a work-piece which includes a male template secured to the under surface of a work piece operating table which is adapted to move to create a tr0- choidal form, and follower means for transmitting motion corresponding to a cam face of the template to a follower table through rotary arms. 1n rough grinding, the follower means can be disengaged from the template for high speed abrasion. while in finishing grinding following the cam face of the template, the force applied to the template is advantageously reduced for prolonged life of the template and high working efficiency.

6 Claims, 4 Drawing Figures PATENTEDSEP ems 3.903.654

FIG!

FIG. 3

PATENTED SEP 91975 sum 2 QF 2 FIG. 2

FIG. 4

GRINDING MACHINE IN WHICH THE FORCE APPLIED TO A GUIDE TEMPLATE IS ADVANTAGEOUSLY REDUCED The present invention relates to a grinding machine 5 and more particularly, to a grinding machine for abrading a trochoidal form surface of a work piece.

in the conventional grinding machines of the above described type for abrading surfaces of work pieces having trochoidal form, the surface of the work piece is abraded by an abrasive wheel adapted to make a noncircular motion by a non-circular form creating motion mechanism which draws a curve similar to that of the surface to be worked of the work piece or by a template having a similar contour to that of the surface to be worked.

However, in the conventional grinding machines of the above described type, it is necessary to position the abrasive wheel accurately on a normal line at the grinding point for the work piece in order to correctly abrade the point to be worked. Moreover, in the above grinding operation, the necessity for driving the abrasive wheel in microns for cutting into the surface to be worked requires a cutting-in feed device with high accuracy, but it is extremely difficult to accurately grind the work piece at high speed with such a cutting-in device attached to a supporting table of the abrasive wheel which makes the complicated non-circular motion.

Additionally, in the prior art grinding machines in which a template is employed for the abrasive wheel to follow for grinding the inner-surface of the work piece, such a template is generally of a female template having a contour similar to that of the surface to be worked. However, the female template of the above described kind has such disadvantages that it is not only difficult to manufacture or repair, but, particularly in grinding the trochoidal form surface, an extremely large pressure is applied to the template by follower means at the projecting portions on the short axis of the two-lobed trochoidal form in the template, resulting in earlier wearing out of the template.

Especially, in the conventional grinding machines of the above described type, the large force required to press the abrasive wheel against the surface of the work piece to be worked during grinding operation is adapted to be directly applied to the template through the follower means, which arrangement extremely shortens the life of the template.

Moreover, since the conventional grinding machines of the above described type are of construction wherein the template is secured on a work piece operating table through a housing, the distance between the head stock and the template is inevitably short, which arrangement requires a large size of the grinding machine itself for installing in-process gauges, autoJoader etc., and besides, the template housing attached on the work piece operating table imparts a larger inertia to the operating table during rotation, thus adversely affecting the high speed operation.

Accordingly, an essential object of the present invention is to provide a grinding machine for abrading a trochoidal form surface of a work piece by a combination of a trochoidal form creation mechanism and a template in which a force to be applied to the template is largely reduced with substantial elimination of the disadvantages inherent in the conventional grinding machines.

Another important object of the present invention is to provide a grinding machine of the above described type in which the template is secured to the under surface of a work piece operating table for easy installation of other necessary devices and for efficient grinding operation.

A further object of the present invention is to provide a grinding machine of the above described type in which a male template having a cam face at the outer periphery thereof is employed for prolonged life and easy repairing of the template.

A still further object of the present invention is to provide a grinding machine of the above described type in which a rough grinding of the surface to be worked only by the trochoidal form creation mechanism, and a finishing grinding of the same by the combination of the trochoidal form creation mechanism and the follower means are readily effected by a single operation with improved accuracy and high working efficiency.

According to a preferred embodiment of the present invention, the work piece secured to the work piece operating table is adapted to move so as to create a trochoidal form with the direction for cutting-in of the abrasive wheel kept constant, so that the trochoidal curve is formed at the point of abrasion with a normal line for the trochoidal form kept positionally stable and with the abrasive wheel adapted to cut into the surface to be worked along a fixed line. On the other hand, a male template having a cam face thereof corresponding to a female trochoidal form surface to be worked is secured to the under surface of the work piece operating table which is adapted to create a trochoidal form, with the movement of a follower corresponding to the cam face of the template being transmitted to a follower table through rotary arm means provided on a main body of the grinding machine so that disadvantages inherent in the conventional grinding machines are advantageously eliminated. In the rough grinding, the follower table can be readily disengaged from the follower means without operating the rotary arms for high speed abrasion.

Furthermore, in the grinding machine of the invention, hydraulic means for applying a first pressure to one end of the rotary arm means in a direction to urge said follower to the cam face of the template, and another hydraulic means for applying a second pressure in a direction opposite to that of the first pressure so as to slide the head stock toward the same end of the rotary arm means are provided, so that the follower is urged against the cam face of the tamplate at a pressure equal to the first pressure minus the second pressure, by which arrangement the life of the template is advantageously prolonged with improved grinding efficiency.

These and other objects and features of the present invention will become apparent from the following description taken in conjunction with the preferred embodiment thereof with reference to the accompanying drawings, in which;

FIG. 1 is a side elevational view, partly in section, of a grinding machine according to the present invention,

P10. 2 is a sectional view, on an enlarged scale, taken along the line 11-" of FIG. 1,

FIG. 3 is a sectional view showing, on an enlarged scale, an important portion of follower means and cut- 3 ting-in means employed in the grinding machine of FIG. 1, and

FIG. 4 is a schematic view explanatory of a trochoidal form creation mechanism employed in the grinding machine of FIG. 1.

Before the description of the present invention proceeds, it is to be noted that like parts are designated by like numerals throughout several views of the accompanying drawings.

For general understanding of the grinding machine of the invention, reference is made to FIG. 1 for brief description of the construction thereof.

it should be noted here that the words rightward, leftword, upward and downward in the description hereinbelow refer to directions as viewed in FIG. 1.

The grinding machine of the invention generally comprises a main body 2 having a flat surface on the upper portion thereof on which a work piece operating table 4 for securing a work piece 1 thereon is slidably disposed, a template 5, for example, a male template secured to the under surface of the table 4, a mechanism 3 disposed in the body 2 below the table 4 for imparting the table 4 a trochoidal form creation motion, a sliding member 7 slidably disposed adjacent to the template 5, a follower 6 fixed at one end of the member 7 adjacent to a cam face a of the template 5, two rotary arms 9 and pivotally mounted on a follower column 8 extending upward at right angles from the leftward surface of the body 2, which rotary arms are each disposed at the lower portion and the upper portion of the follower table on' the axes parallel to each other with the upper end of the arm 9 and the lower end of the arm 10 adapted to engage with or disengage from each other so that when the lower arm 9 is rotated clockwise, the upper arm 10 is rotated counter clockwise or vice versa, a rectangular lift table 16 slidably mounted at the back of the body 2 by guide means mentioned later for upward or downward movements, on which lift table 16 a head stock 22 with an abrasive wheel spindle 23, a follower table and an abrasive wheel cutting-in device 17 are disposed in a row at the lower part of the lift table. The spindle 23 to the lower end of which an abrasive wheel 24 is fixed is rotatably received in a wheel head 25 which is in turn slidably received for lateral movement thereof in the head stock 22 by guide means mentioned later and is connected for rotation through a belt 29 to a motor 28 slidably mounted, for example, by guide means on the lift table 16 for upward or downward movement.

It should be noted here that the lift table is movable upward or downward with the head stock 22 having the spindle 23, the follower table 20, the cutting-in device 17, and the motor 28 disposed thereon, whereas on the lift table 16 the cutting device 17 remains stationary while the follower table 20, the head stock 22 and the motor 28 are only laterally movable and that the abrasive wheel spindle 23 supported in the head stock 22 is movable upward or downward by a predetermined distance besides the lateral movement thereof together with the head stock 22.

It should also be noted that the sliding member 7, the rotary arms 9 and 10, the follower table 20 and the head stock 22 are on the same plane normal to the flat horizontal surface of the main body 2, so that the movement of the sliding member corresponding to the cam face 50 of the template 5 can be transmitted through the follower 6 and the rotary arms 9 and 10 to the follower table 20, and that the abrasive stone 24 is cut into a surface 10 of the work piece I in a direction parallel to the movement of the sliding member 7.

Detailed construction of the grinding machine of the invention will be described hereinbelow.

Referring to FIGS. 1 through 3, there is shown the grinding machine G of the invention for grinding the work piece 1 having a two-lobed trochoidal surface la to be worked, in which grinding machine G the work piece operating table 4 which is associated with the trochoid creating motion mechanism 3 mentioned later is slidably, horizontally disposed on the horizontal upper surface of the main body 2 of the grinding machine G for moving the work piece 1 to form a two-lobed trochoidal curve. To the lower portion of the operating table 4, there is fixed, by suitable means, the male template 5 having, on the outer periphery 50 thereof, a corrected two-lobed trochoidal curve formed by revising, for actual use, the above two-lobed trochoidal curve to be drawn by the mechanism 3.

On the upper surface of the main body 2, there is also slidably disposed the sliding member 7 which moves on a normal line for the trochoidal form mentioned later, and which has the follower 6, at one end 7b thereof, adjacent to the template 5 with the follower 6 adapted to contact and follow the outer periphery or cam face 50 of the template 5. To the follower column 8 upwardly extending at right angles from the surface of the main body 2 at the left portion of the body 2 in FIG. I, the lower rotary arm 9 and the upper rotary arm 10 are pivotally connected by corresponding pins [la and llb with one end of each of the arms 9 and 10 adapted to engage each other and with the other lower end of the arm 9 facing the end 7c of the sliding member 7, so that when the lower arm 9 is rotated clockwise, the upper arm'10 is rotated counter clockwise. The other upper end 10a of the rotary arm 10 is located between a piston 12a for a template depressing cylinder 12 fixed to the follower column 8 and the follower table 20 mentioned later for pressing the end of the arm 10 against the follower table 20 upon actuation of the piston 12a and simultaneously for pressing the end 9a of the rotary arm 9 against the end 70 of the sliding member 7 so as to move the member 7 toward right in FIG. 1 along the normal line and to urge the follower 6 of the member 7 against the cam face 5a of the template 5. Accordingly, when the work piece operating table 4 is rotated in the above state, the follower 6 moves along the cam face 5a of the template 5 with the sliding member 7 moved along the normal line for the trochoidal form so as to push the lower end 9a of the arm 9 and to turn the arm 9 clockwise which in turn rotates the arm 10 counterclockwise, and thus, motion corresponding to the cam face 5a of the template 5 due to the rotation is transmitted to the follower table 20. A piston rod extending from a cylinder 13 fixed to the main body 2 at a position above the sliding member 7 is adapted to depress, upon actuation of the cylinder 13, a projection 7a extending upwardly at right angles from the end 7c of the member 7 for spacing the member 7 and consequently the follower 6 away from the template 5.

Referring particularly to FIG. 2, a lift table 16 is slidably mounted on head stock guides 14 provided at the back of the body 2 for vertically moving a head stock 22 and is adapted to move upward or downward by the actuation of a piston rod (not shown) of a cylinder 15.

The lift table 16 is provided with cutting-in means 17 with the follower table 20 and the head stock 22 also slidably mounted on the table 16 so as to be laterally movable through, for example, guide means (not shown).

It should be noted here that, upon raising the lift table 16, the follower table 20, the head stock 22 with the spindle 23 associated with the motor 28 fiirough a belt 29, and the cutting-in means 17, each mounted on the table 16 is moved upword together with the table 16 for raising the spindle 23 having the abrasive wheel 24 fixed at the end thereof so that the work piece 1 can be fixed on the work piece operating table 4 and that upon lowering the table 16, the same are lowered together with the table 16 for grinding operation.

It should also be noted that the cutting-in means 17 is adapted to move the head stock 22 leftward toward the follower table 20 in FIG. 1 for bringing the abrasive wheel 24 into contact with the surface 1a to be worked of the work piece 1, and that for urging the abrasive wheel 24 against the surface In to be worked, both the head stock 22 and the follower table 20 are simultaneously moved leftward in FIG. 1 by a follower device 37 mentioned later.

A wheel head 25 in which an abrasive wheel spindle 23 extending in a direction normal to the surface of the operating table 4 is rotatably recieved is slidably mounted, for upward and downward movements, on the head stock 22 through traverse guides 26, which wheel head 25 is adapted to move vertically upward or downward upon operation of a piston rod of an abrasive wheel traversing cylinder 27 disposed above the head stock 22 for abrading the entire surface 1a of the work piece 1 by means of the abrasive wheel 24 fixed at the lower end of the spindle 23.

On the lift table 16, an abrasive wheel spindle driving motor 28 for rotating the abrasive wheel spindle 23 through a belt 29 is mounted through, for example, guide means (not shown) provided apart from the guides 14 so as to be slidably, laterally movable in association with the head stock 22 so that the spindle 23 is always driven irrespective of the movement of the former.

in the cutting-in device 17 mounted on the lift table 16, a rotary shaft 170 fixed to an operating handle 18 (FIG. 1) is connected to one end of an operating shaft 30 through a reduction mechanism 19 which includes bevel gears 19a and 19b engaging each other. On the other hand, in the head stock 22, a rotating member 33 having, at one end thereof, a threaded portion 330 (FIG, 3) which threadedly engages a bore 21 formed in the follower table 20 is supported by bearings 32. A bore 34 is centrally formed at the other end of the member 33, in which bore 34 a retaining member 35 is received and fixed therein by a key 36 and a cap plate 36. The retaining member 35 is centrally formed with a bore 350 which extends through the member 35, into which bore 350 the other end of the operating shaft 30 is slidably received through ball means (not shown), but is prevented from rotation within the member 35 by a spline 31 provided on the shaft 30 to form the so called ball and spline engagement therebetween.

It should be noted here that the rotating member 33 and the operating shaft 30 are coaxial and directed in a direction parallel to the normal line of the trochoidal form.

Accordingly, upon rotation of the handle 18, the rotating member 33 is rotated to a slight degree with the threaded end 33a thereof threaded into the bore 21 and consequently with the head stock 22 shifted toward the follower table 20 through, for example, guide means (not shown) for the abrasive wheel 24 to be cut into the surface 1a of the work piece 1. it is needless to say that the head stock 22 is spaced away from the follower table 20 upon rotation of the handle 18 in the opposite direction to the above.

The follower device 37 comprises a follower cylinder 38 secured to the lift table 16 and a piston 39 received in the cylinder 38 with a piston rod 39a of the piston 39 fixed to a corresponding portion of the head stock 22 to urge the head stock 22 leftward when the cylinder 38 is actuated as mentioned below. Upon introduction of a pressurised fluid into the right side chamber 400 of the cylinder 38 in FIG. 3 through hydraulic means (not shown), the piston rod 39a and consequently the head stock 22 is moved leftward with consequent leftward movement of the follower table 20 threadedly engaging the head stock through the rotating member 33, thus continuously depressing the head stock 22 and the table 20 leftward for urging the abrasive wheel 24 against the surface la to be worked, while the same is moved rightward when the pressure fluid is introduced into the chamber 40b.

A follower cylinder 41 for trochoidal form creation is disposed in a direction parallel to the sliding member 7 at the lower part of the follower table 20 adjacent to the upper end 10a of the arm 10. When the work piece operating table 4 is rotated with a piston rod 42 of the cylinder 41 projected from the cylinder 41 so as to urge the projecting end of the rod 42 against the upper end of the rotary arm 10 by the pressing force of the follower device 37, and with a piston rod 42 of an operating cylinder 41' for the trochoidal form creation, which is provided on the upper part of the follower table 20, retracted, so as to space the end of the rod 42' away from the follower column 8, motion arising from the displacement of the template 5 due to the rotation thereof is transmitted to the follower table 20 through the follower 6 at a force equivalent to pressure difference between the pressure exerted by the template depressing cylinder 12 and the pressure exerted by the follower device 37 for abrading the work piece 1 on the table 4 so as to create the trochoidal form and also to follow the template 5.

On the contrary, if the feeding of the follower table 20 is restricted at a predetermined position with the piston rod 42 of the creation and follower cylinder 41 retracted for spacing the rod 42 away from the arm 10 and with the piston rod 42' for the operating cylinder 41' for the trochoidal form creation projected for engaging the rod 42' vn'th the follower column 8, the work piece 1 can be abraded only for the creation of the trochoidal form without following the template 5. An inprocess gauge 43 is provided in a position suitable for the measurement of the surface of the work piece 1 being worked.

In other words, the cylinder 41' is for limiting the leftward movement of the follower table 20 so that the surface In of the work piece 1 is abraded only to form the trochoidal form, while the cylinder 41 is for establishing engagement between the follower table 20 and the upper rotary arm 10 for abrading the surface In following the template while the work piece 1 is rotated to create the trochoidal form.

The mechanism 3 for the creation of the trochoidal form is described hereinbelow.

The mechanism 3 disposed in the lower part of the main body 2 below the work piece operating table 4 includes a driving shaft 44 which comprises an upper portion 45 integrally formed with a lower portion 45' thereof with the axis of the upper portion 45 deviated from the axis of the lower portion 45' by a distance e and which is rotatably supported in a direction parallel to the abrasive wheel spindle 23 by a bearing 470 at the upper portion 45 and by a bearing 47b at the lower por tion 45 respectively, a pinion 46 fixedly mounted on the shaft 44 on the upper portion 45 thereof between the bearings 47a and 47b, and a boxlike connecting member 49 rotatably mounted at an approximately central portion thereof, on the upper portion 45 of the shaft 44 through an upper bearing 48:: and a lower bearing 48b. In the inner portion of the connecting member 49 at the right of the shaft 44 in FIG. 1, a shaft 51 extending in a direction parallel to the axes of the shaft 44 and having a pinion 50, which engages the pinion 46 of the shaft 44, fixedly mounted thereon is rotatably supported by the member 49 through an upper bearing 51a and a lower bearing 51b with the upper end of the shaft 51 secured to the lower central portion of the work piece operating table 4, while in the inner portion of the member 49 at the left of the shaft 44, a pinion 53 is fixedly mounted on a shaft 54 extending in a direction parallel to the axes of the shaft 44 and rotatably supported by the member 49 by an upper bearing 55a and a lower bearing 55b, which pinion 53 engages the pinion 46 through an intermediate gear 56. A connecting plate 57 is fixedly mounted on the upper end of the shaft 54 which extends through the member 49, while a pin 58 is rotatably mounted, through a bearing 57', in the plate 57 at a position deviated from the axis of the shaft 54 by a predetermined distance, the upper end of which pin 58 extending through the plate 57 is rotatably connected to a sliding member 60 slidably received in a groove 59 formed in the main body 2 in a direction parallel to the sliding member '7.

ln the above case, it is known that the work piece 1 being rotated by the gear 50 forms a two-lobed trochoidal curve above the driving shaft 44 of the pinion 46 which is rotating at an angular velocity two times as large as that of the work piece 1. Accordingly, if the cutting-in feeding of the abrasive wheel 24 into the surface la of the work piece 1 is made on a line connecting an engaging point A between the pinion 46 and the gear 50, and the axis B (creating point of a trochoidal form) of the lower portion 45' of the driving shaft 44, which line is, in other words, a normal line N for the trochoidal form, the surface of the work piece 1 can be geometrically, accurately worked into the trochoidal form.

However, it should be noted that since the axis of the upper portion 45 of the shaft 44 is deviated from that of the lower portion 45 of the same, the normal line N is not stable, thus necessitating the position of the abrasive wheel 23 to be varied according to the positional variation of the normal line N, which makes it impossible to carry out accurate abrading in strict accordance with the trochoidal form.

The above disadvantage is completely eliminated in the mechanism 3 for the creation movement of the trochoidal form of the invention in the manner as described hereinbelow.

Referring also to H6. 4, in the mechanism 3 of the invention, the groove 59 is formed in the body 2 on the normal line N connecting the engaging point A between the gear 50 and the pinion 46, and the axis B of the lower portion 45 of the shaft 44, while the gear 50, the pinion 46, the intermediate gear 56 and the pinion 53 are rotatably supported in the connecting member 49 as described earlier with the upper end of the shaft 54 for the pinion 53 secured to the connecting plate 57 and with the connecting plate 57 in turn rotatably connected, at one end thereof through the pin 58, to the sliding member 60 slidably received in the groove 59 so that points A, B and C, and the points A, D and E in FIG. 4 fomi a similar triangle to each other. Since the numbers of teeth for the pinions 46 and 53 are the same, when the pinion 46 is rotated in a predetermined direction about the driving shaft 44, the pinion 53 is also rotated at the same angular velocity as the pinion 46, in which case, as the connecting plate 57 is limited in its movement by the presence of the sliding member 60, the gear 50 rotates, with the connecting member 49 rocking about the engaging point A so that the work piece 1 forms the trochoidal curve above the driving shaft 44.

As is seen from the above description, since the work piece 1 secured to the work piece operating table 4 is adapted to form the trochoidal curve above the driving shaft 44 by forming the groove 59 in the direction of the normal line N, the surface la of the work piece 1 can be accurately worked for trochoidal form by causing the abrasive wheel 24 to cut into the surface la to be worked.

By this arrangement, the work piece 1 is secured on the work piece operating table 4 with the piston rod 12a for the depressing cylinder 12 extended to a predetermined degree so as to move the sliding member 7 rightward in FIG. 1 for contacting the follower 6 with the cam face 5a of the template 5, after which the pressure fluid is introduced into the chamber 400 in the cylinder 38 for moving the follower table 20 and the head stock 22 toward the left in the drawing. Since the pressing force Pb by the cylinder 38 is smaller than the pressing force Pa by the template depressing cylinder 12, the follower 6 is urged against the cam face 50 of the template 5 at a pressure P Pa Pb.

it should be noted here that the relation of forces acting on the various part of the grinding machine during operation can be represented by the following equation where P! is a force for depressing the follower 6 to the template 5, Pa is the force by the cylinder 12 for depressing the template 5, pb is the force by the cylinder 38 for moving the follower table 20 and headstock 22 toward the left in FIG. 1, Pc is a force for pressing the abrasive wheel 24 against the surface la of the work piece 1, and Pd is a force depressing the upper end of the rotary arm 10 toward left in FIG. 1. The force Pd varies as follows during the operation of the grinding machine.

1. Initially, the abrasive wheel 24 is not in contact with the surface 1a of the work piece 1. Therefore, Pc 0 and hence P! Pa Pb.

2. Subsequently, when the abrasive wheel 24 is fed for cutting-in operation, the force Pc is produced.

Accordingly, Pr Pa (Pb P) Pa Pb F0. 3. Finally, after completion of the grinding operation,

Pc equals 0. Pt Pa Pb When the driving shaft 44 is rotated in the above state by a driving motor (not shown), the work piece 1 secured to the work piece operating table 4 is moved above the shaft 44, forming the trochoidal curve. On the other hand, as the table 4 rotates, the follower table 20 is moved, through the rotary arms 9 and 10, correspondingly to the movement of the follower 6 along the cam face 50 of the template 5. Accordingly, when the head stock 22 is moved toward the left in FIG. 1 by the cutting-in device 17 with the abrasive wheel spindle 23 traversed by the cylinder 27 and with the spindle 23 rotated by the motor 28, the abrasive wheel 24 abrades the surface 1a to be worked along the entire width of the surface la for very accurate abrasion of the work piece 1, since the follower table 20 is limited in its movement by the rotary arm 10.

The above described abrasion based on the template may be required only in finishing the surface la, so that in rough abrading, the cylinder 13 is operated with the piston rod 130 thereof engaging the projection 7a of the sliding member 7 and with the piston rod 12a of the depressing cylinder 12 retracted for spacing the follower 6 away from the cam face 50 of the template 5 and simultaneously for moving the upper end 100 of the rotary arm away from the follower table 20. In the above state, when the follower cylinder 38 is operated as described earlier with the piston rod 42 of the creating operation cylinder 41' extended, the follower table is independent of the template 5, so that the surface la of the work piece 1 can be ground with the abrasive wheel 24 rotated by the driving motor (not shown) running at high speed. It is needless to say that the abrasive wheel 24 can be cut into the surface la to be worked in the same manner as that described earlier.

As is clear from the foregoing description, in the grinding machine of the invention, since the template is adapted to be secured to the under surface of the work operating table, the upper surface is free from any obstacle, by which arrangement auto-loading devices, in-process gauges, etc. can be readily attached.

As the cam face is formed on the outer periphery of the template for correspondingly moving the follower table through the rotary arms, the short axis of the trochoidal from coincides with the concave portion of the trochoidal form with consequent less pressure applied thereto by the follower, and the cam face is readily repaired when worn out.

Moreover, since the work piece forms the trochoidal curve at the point of grinding through the rotation of the work piece operating table, the engagement between the template and the follower can be released by operating the cylinder for trochoidal form creation with the piston rod of the template depressing cylinder retracted and with the cylinder for spacing the follower away from the template operated, which arrangement is effective for high speed grinding with the wearing out of the template advantageously prevented, resulting in improved productivity in the grinding operation.

Furthermore, in the grinding machine of the present invention, the force Pb for pressing the abrasive wheel against the work piece is not directly applied to the template through the follower in finishing grinding, but is applied in the direction to move the follower away from the template. in other words, the above force Pb is adapted to be smaller than the pressing force Pa by the depressing cylinder. Accordingly, the force P for pressing the follower against the template is equal to Pa minus Pb,'by which the force applied to the template is reduced to a great extent with remarkably prolonged life of the template.

Although the present invention has been fully described by way of example with reference to the attached drawings, it is to be noted that various changes and modifications are apparent to those skilled in the art. Therefore, unless otherwise such changes and modifications depart from the scope of the present invention, they should be construed as included therein.

What is claimed is:

l. A grinding machine for abrading a trochoidal form surface of a work piece which comprises a work piece operating table slidably mounted, for securing a work piece thereon, on a surface of a main body of said grinding machine, said work piece operating table being adapted to move so as to form a trochoidal curve on a normal line for said trochoidal curve, a template having a cam face thereof corresponding to said trochoidal form and secured to said work piece operating table at a side of the latter opposite to that on which said work piece is secured, a follower member which is in sliding contact with said cam face of said template and which is slidable to a direction of movement of an abrasive wheel, rotary arm means whose one end is as sociated with said follower member so as to urge said follower member to said cam face or to space said follower member away from said cam face, means for applying a first pressure to the other end of said rotary arm means in a direction to urge said follower member to said cam face of said template, a head stock supporting a spindle of said abrasive wheel, means for applying a second pressure in a direction opposite to that of said first pressure so as to slide said head stock to a direction toward said other end of said rotary arm means for urging said head stock against said other end of said rotary arm, said follower member being urged against said cam face of said template at a pressure equal to said first pressure minus said second pressure since said second pressure is smaller than said first pressure.

2. A grinding machine as claimed in claim 1, wherein said rotary arm means comprises an upper rotary arm and an lower rotary arm pivotally mounted on a main body of said grinding machine with one end of each of said arms engaging each other so that when said lower arm is rotated clockwise, said upper arm is rotated counterclockwise.

3. A grinding machine as claimed in claim 1, wherein said follower member is secured to one end of a sliding member which is slidable in the same direction as the direction of movement of said abrasive wheel with the other end of said sliding member contacting said one end of said rotary arm means.

4. A grinding machine as claimed in claimed in claim 3, wherein said rotary arm means comprises a plurality of rotary arms pivotally connected to said main body.

5. A grinding machine as claimed in claim 1, wherein a follower table laterally slidable is further disposed between said head stock and said rotary arm means, said follower table being further provided with a first cylinder for creating and following said trochoidal form and a second cylinder for creating said trochoidal form, so that when a piston rod of said first cylinder is projected means with said piston rod of said second cylinder projected for limiting feeding of said follower table at a predetermined position, said follower member is kept away from said cam face for abrading only for said trochoidal form creation.

6. A grinding machine as claimed in claim 1, wherein said abrasive wheel is further provided with cutting-in means, said cutting-in means being associated with said follower table for lateral movement of the latter. 

1. A grinding machine for abrading a trochoidal form surface of a work piece which comprises a work piece operating table slidably mounted, for securing a work piece thereon, on a surface of a main body of said grinding machine, said work piece operating table being adapted to move so as to form a trochoidal curve on a normal line for said trochoidal curve, a template having a cam face thereof corresponding to said trochoidal form and secured to said work piece operating table at a side of the latter opposite to that on which said work piece is secured, a follower member which is in sliding contact with said cam face of said template and which is slidable to a direction of movement of an abrasive wheel, rotary arm means whose one end is associated with said follower member so as to urge said follower member to said cam face or to space said follower member away from said cam face, means for applying a first pressure to the other end of said rotary arm means in a direction to urge said follower member to said cam face of said template, a head stock supporting a spindle of said abrasive wheel, means for applying a second pressure in a direction opposite to that of said first pressure so as to slide said head stock to a direction toward said other end of said rotary arm means for urging said head stock against said other end of said rotary arm, said follower member being urged against said cam face of said template at a pressure equal to said first pressure minus said second pressure since said second pressure is smaller than said first pressure.
 2. A grinding machine as claimed in claim 1, wherein said rotary arm means comprises an upper rotary arm and an lower rotary arm pivotally mounted on a main body of said grinding machine with one end of each of said arms engaging each other so that when said lower arm is rotated clockwise, said upper arm is rotated counterclockwise.
 3. A grinding machine as claimed in claim 1, wherein said follower member is secured to one end of a sliding member which is slidable in the same direction as the direction of movement of said abrasive wheel with the other end of said sliding member contacting said one end of said rotary arm means.
 4. A grinding machine as claimed in claimed in claim 3, wherein said rotary arm means comprises a plurality of rotary arms pivotally connected to said main body.
 5. A grindIng machine as claimed in claim 1, wherein a follower table laterally slidable is further disposed between said head stock and said rotary arm means, said follower table being further provided with a first cylinder for creating and following said trochoidal form and a second cylinder for creating said trochoidal form, so that when a piston rod of said first cylinder is projected so as to engage said other end of said rotary arm means, by said second pressure during rotation of said work piece operating table, with a piston rod of said second cylinder retracted, motion corresponding to said cam face is transmitted to said follower table through said follower member at said pressure equal to said first pressure minus said second pressure for adrading creating and following said trochoidal form, and when said piston rod of said first cylinder is retracted so as to space away from said other end of said rotary arm means with said piston rod of said second cylinder projected for limiting feeding of said follower table at a predetermined position, said follower member is kept away from said cam face for abrading only for said trochoidal form creation.
 6. A grinding machine as claimed in claim 1, wherein said abrasive wheel is further provided with cutting-in means, said cutting-in means being associated with said follower table for lateral movement of the latter. 